Melatonin (CAS-73-31-4), imported in bulk form. The subject product, Melatonin, is defined in the 28th edition of Dorland’s Illustrated Medical Dictionary as “[a] hormone synthesized by the pineal gland that produces lightening of the dermal pigmentation in adult amphibians … . Secretion increases duuring exposure to light; in mammals it influences hormone production and in many species regulates seasonal changes such as reproductive pattern and fur color. In humans it is implicated in the regulation of sleep, mood, puberty, and ovarian cycles.”
[1] Please importantly note that only the relevant portion of the related is displayed above. You may refer to the said customs ruling for the entire ruling explanation.
[1]. https://rulings.cbp.gov/ruling/H86555